Switch for drive-in theatre speakers



.July 3, 1956 o. 0. MELKON 2,753,410

SWITCH FOR DRIVE-IN THEATRE SPEAKERS Filed Feb. 21, 1955 United States Patent 2,753,410 SWITCH FOR DRIVE-IN THEATRE SPEAKERS Onnig D. Melkon, South Weyrnouth, Mass. Application February 21, 1955, Serial No. 489,463 6 Claims. (Cl. 200-6158) This invention relates to electric switches and in particular to switches for controlling the circuits of individ ual portable loud speakers of the type used in drive-in movie theatres.

in the usual drive-in theatre the sound accompanying the film is brought to the customers through a number of individual loud speakers which are adapted to be temporarily mounted in the customers automobiles. A

way off, or even to turn down the volume when they leave. Careless customers also throw the speakers on the ground instead of returning them to the proper receptacles. The waste of current is an important factor in the cost of operation of the theatre. Also the noise from unused speakers which are left turned on may disturb other customers and people living in the neighborhood. Consequently, the theatre operator is obliged to send ushers through the theatre to turn off unused speakers at frequent intervals during the performance, and to check on all the speakers after the performance is over.

The general object of this invention is to provide a switch which will automatically shut off a loud speaker of this type when it is not in use. Other objects are to provide a switch which will operate to shut off the speaker whenever it is removed from the car, whether or not the speaker is replaced in its proper receptacle and regardless of its position, which is simple, reliable and foolproof, and which can be readily installed on existing speakers. Other objects and advantages will be apparent from the description which follows.

The switch here disclosed is intended to be mounted in the arm of the speaker case, and consists in general of a pair of spaced leaf contacts and an operating button which is arranged to project through the under side of the arm and is pushed upward by the edge of the car door or window when the speaker is in place on the car. The button carries a bridging contact which, when the button is pushed up, engages the leaf contacts to close the speaker circuit. The button falls down of its own weight when the speaker is removed from the car. Preferably one of the leaf contacts is disposed lower than the other and is bent upward when the button is pushed up. The button is too light to bend this lower contact and close the circuit if the speaker is turned upside down. The switch parts are suitably insulated and are mounted in a bail which fits inside the arm and is attached to the speaker housing.

In the drawings illustrating the invention:

Fig. 1 is a side view of the speaker, the arm and switch being shown partly in cross-section;

Patent-ed July 3, P356 Fig. 2 is a similar view of the arm and switch showing the switch in closed position;

Fig. 3 is a cross-section through the arm along line 3-3 of Fig. 1; and

Fig. 4 is a cross-section along line 44 of Fig. 3.

The speaker, which is not shown in detail, is mounted in a conventional housing it; having a hollow, horizontal arm 11 to the outer end of which is connected a depending plate 12. When the speaker is in use, the arm is ordinarily hooked over the car door, indicated by the dotted line 13 in Fig. 2, with the plate 12 lying to the outside of the door and the housing 16 on the inside. T he speaker can be hung in a similar manner on a window, mirror, handle, or other suitable projection on the car. The usual volume control knob 14, which may also control a conventional shut-off switch, is mounted on the face of the speaker opposite the arm, or in any other suitable location. A U-shaped bail 15, which supports the switch elements, is mounted in the arm 11. The bail is preferably made of a soft metal which can be easily bent, and its ends 15a and 15b are initially straight and are bent at installation to fit inside the speaker housing at the base of the arm, "asjshown in Fig. 1, so that the bail can be adapted to fit arms of various lengths. The ends 15a and 15b are attached to the housing by any convenient means such as screws or rivets.

An opening 16 is cut in the lower wall 11a of the arm, and the bail has in its lower wall a corresponding opening 17 which is aligned with opening 16. A rectangular block i8, which constitutes the operating button for the switch is movably mounted in these openings. As shown in Fig. 4, this block has shoulders 19 and 20 along two sides at the top which rest on the bottom wall 150 of the bail on either side of the openings. These shoulders retain the block in the arm. The block is made of insulating material and has a conductive bridging plate 21 mounted on its top.

Mounted on lower wall 150 of the bail is an insulating base block 22. The base block may be fastened to the bail in any convenient manner and is here shown as secured by bent over tongues 23 and 24 which are stamped out of the bail. A pair of leaf contacts 25 and 26 are mounted on this base block and have free ends 25a and 26a, respectively, projecting across the openings 16 and 17. These contacts are made of flexible spring material, such as one of the brass or bronze alloys ordinarily used for leaf contacts in relays, and are attached to the base block by means of screws 2'7 and 28 which also serve to secure a pair of wiring lugs 2E? and A cross bar 31 of insulating material is screwed to the base block and holds the leaf contacts down in the region just to one side of the openings. When block 18 is in its down position, the end 2M of contact 26 may lie approximately horizontally or may be bent slightly downward, as shown in Fig. 1, while end 25a of contact 25 is bent upward. The end 26a may be made to en age plate 21 when block 18 is down or may clear the plate.

When block 18 is pushed up into the arm by engagement with the car door, as shown in Fig. 2, end 26a is carried up into alignment with end 25a so that the bridging plate engages both contacts. The weight of the speaker and housing as a whole is sufiicient to bend end 26a, even though the leaf contact 26 may be made of relatively stiff spring metal. Block 18, however, is relatively light, and its weight would not suflice to bend end 26a into alignment with end 25a if the speaker were to be taken off the door and placed upside down.

The switch is connected into the speaker circuit by means of suitable wiring which is attached to lugs 29 and 30. As can be readily understood, if the switch is wired in series with the volume control, the speaker will operate only when contact ends 26a and 250 are bridged by plate 21, whether or not a conventional shut-off switch is incorporated in the speaker so as to be operated by knob 14, and regardless of the position of the latter.

The operation of the switch here shown requires no extra effort on the part of the user, as he merely hangs the speaker on the car door or in some other suitable location and adjusts the volume control knob as he has always done. It makes no difference to him whether the volume control knob is left in the on or off position, as he will ordinarily have to readjust the volume after the speaker warms up in any case.

As soon as the speaker is removed from the car, the current is shut off, regardless of what the user does, even if he merely drops the speaker on the ground, instead of returning it to its proper receptacle. The switch is thus entirely foolproof and results in a considerable saving to the theatre operator in current, wear on the speakers,

and labor.

I claim:

1. A switch, for a portable loud speaker of the type having a supporting arm adapted to engage a generally horizontal surface on an automobile, comprising: an opening in the bottom of said arm; a switch operating member mounted in said opening and movable with respect to the arm, said member being adapted to engage and be pushed up by said surface when the arm engages the surface; a pair of leaf contacts mounted in said arm; and a bridging member carried by said operating member and adapted to engage both said contacts when the operating member is pushed up by said surface, said leaf contacts being normally disposed in such positions that the bridging member cannot engage both at once, and one of said contacts being movable by said operating member when it moves upward, to a position in which the bridging member engages both contacts.

2. A switch, for a portable loud speaker of the type having a supporting arm adapted to engage a generally horizontal surface on an automobile, comprising: an opening in the bottom of said arm; an operating block mounted to move up and down in said opening and being adapted to engage and be pushed upward with respect to the arm by said surface when the arm engages the surface; a pair of leaf contacts overlying said opening, and a bridging plate mounted on said block and adapted to engage both said contacts when the block is pushed up, one of said contacts being normally disposed lower than the other and being bendable by said block, when it moves upward, to the same level as the other contact.

3. A switch as described in claim 2, said bendable contact being too stiff to bend to the level of the other under the weight of the block when the speaker is turned upside down.

4. A switch for a portable loud speaker of the type having a hollow supporting arm adapted to engage a generally horizontal surface on an automobile, comprising: a U-shaped bail mounted in said arm, having legs disposed along the top and bottom of the arm; an opening in the bottom of the arm; an opening in the bottom leg of the bail, aligned with the arm opening; a block mounted in said openings and movable up and down therein; said block being adapted to engage and be pushed up with respect to the arm by said surface when the arm engages the surface; an insulating plate mounted on said bottom leg; a pair of leaf contacts mounted spaced apart on said plate and having free ends projecting across said openings; and a bridging plate mounted on the top of said block and adapted to engage both said contacts when the block is pushed up.

5. A switch as described in claim 4, the free end of one of said contacts being disposed at about the level of said plate when the block is down, and the free end of the other contacts being disposed above said level, said first named end being movable upward to the level of the other by pushing up the block.

6. A switch as described in claim 4, the block and the openings being generally rectangular and the block having shoulders which rest on said bottom leg when the block is down to retain the block on the arm.

References Cited in the file of this patent UNITED STATES PATENTS mil 

